Oxybutynin and its derivatives are applicable as a bronchodilator or a remedy for pollakisuria. Also, oxybutynin exerts a direct antispasmodic effect on various forms of smooth muscle, mainly by inhibiting the action of acetylcholine on smooth muscle as an anti-cholinergic drug and the like. Oxybutynin is marketed in hydrochloride form. Oxybutynin known as [α-cyclohexyl-hydroxy-benzeneaceticacid-4-(diethyl amino)-2-butynyl ester] is given below:

The U.S. Pat. No. 3,176,019 ('019) discloses about 4-amino-2-butynol esters and their derivatives, particularly about oxybutynin hydrochloride. It also reveals about the synthesis of oxybutynin, wherein, the methyl phenyl cyclohexyl glycolate is reacted with 4-diethylamino-2-butynylacetate in presence of base to yield oxybutynin followed by further workup. Further, it is treated with 2N HCl solution to form hydrochloride salt. It is recrystallised by employing ethyl acetate or water to obtain pure oxybutynin hydrochloride. Further, the US patent '019 unveils about the reaction of propargyl-2-cyclohexyl-2-hydroxy-2-phenyl acetate, p-formaldehyde and diethyl amine in dry dioxane to obtain crude product of oxybutynin. The dry hydrogen chloride gas is passed through the ether solution of oxybutynin to yield the oxybutynin chloride as precipitate.
According to the prior art process oxybutynin is obtained as oil, which contains lot of impurities, therefore, it needs to purify high vacuum distillation. Also, the resultant oxybutynin base is having a low melting point, which may decompose during high vacuum distillation. Further, the existence of any polymorphism in oxybutynin is not disclosed in prior arts. In light of the foregoing, a need exists in the art for inventing a new form and the process thereof.